This invention relates to the repair of a tricuspid valve exhibiting valve regurgitation. More particularly, the invention relates to apparatus and methods suitable for a less invasive repair of a tricuspid heart valve.
FIG. 1 is a cross-sectional view of the left and tight ventricles of a human heart 14 in diastole. The figure shows how the tricuspid valve 21 connects together the chambers of the right atrium and the right ventricle, and controls the flow of blood between these two chambers.
FIG. 2 is a schematic view from above of a tricuspid valve of a human heart, showing the three leaflets of the valve namely the anterior leaflet 52, posterior leaflet 56, and the septal leaflet 54, which all converge on a common point of meeting at the center of the valve.
As used herein, the term “endovascular,” refers to procedure(s) of the present invention that are performed with interventional tools and supporting catheters and other equipment introduced to the heart chambers from the patient's arterial or venous vasculature remote from the heart. The interventional tools and other equipment may be introduced percutaneously, i.e., through an access sheath, or may be introduced via a surgical cut down, and then advanced from the remote access site through the vasculature until they reach heart 14. As such, the methods and apparatus described herein generally do not require penetrations made directly through an exterior heart muscle, i.e., myocardium, although there may be some instances where penetrations will be made interior to the heart, e.g., through the interatrial septum to provide for a desired access route.
The atrioventricular valves are each located at a junction of the atria and their respective ventricles. The atrioventricular valve extending between the right atrium 30 and the right ventricle 12 has three valve leaflets (cusps) and is referred to as the tricuspid or right atrioventricular valve 21. The atrioventricular valve between the left atrium 32 and the left ventricle 10 is a bicuspid valve having only two leaflets or cusps 34 and is generally referred to as the mitral valve 20.
During operation of the heart 14, the valve leaflets open during diastole when the heart atria fill with blood, allowing the blood to pass into the ventricle. During systole, however, the valve leaflets are pushed together such that the free edges of the leaflets are closed against each other along a line of coaptation to prevent the back-flow of blood into the atria. Back flow of blood or “regurgitation” through the mitral valve 20 is facilitated to be prevented when the leaflets 34 are closed, such that the mitral valve 20 functions as a “check valve” which prevents back-flow when pressure in the left ventricle 10 is higher than that in the left atrium 32.
The mitral valve leaflets 34 are attached to the surrounding heart structure along an annular region referred to as the valve annulus 40. The free edges 36 of the leaflets 34 are secured to the lower portions of the left ventricle 10 through tendon-like tissue structures, known as chordae tendineae or chordae 42. The chordae 42 are attached to the papillary muscles which extend upwardly from the lower portions of the left ventricle and interventricular septum 46.
The tricuspid valve is similar to the mitral valve, but it is more complex in that it has three leaflets, as described above.
Tricuspid regurgitation, i.e., backward leakage of blood at the tricuspid heart valve, is typically caused by defective coaptation of the three leaflets against each other, and results in reduced pumping efficiency. Diagnosis of tricuspid regurgitation can be performed using visualization with transesophageal echocardiography or by echocardiography. In particular, defective leaflet coaptation and the site and direction of the regurgitant flow can be examined to evaluate likely modes of failure.
Tricuspid valve prolapse, i.e. degeneration of tricuspid valve leaflets, is the most common cause of tricuspid regurgitation in North America. Many cases of regurgitation can be repaired by modifications of the original valve in a procedure generally referred to as valvuloplasty. Valves that are heavily calcified or significantly compromised by disease may need to be replaced.
Successful methods have been developed for performing less invasive repairs to the mitral valve. In particular, such repairs can be performed on a beating heart such that the patient does not have to be placed on cardiopulmonary bypass.
One approach suitable for mitral valve repair is to introduce instruments via a transcatheter procedure into the heart by direct introduction through a passageway through the wall of the heart. Suitable gripping and fastening instruments have appropriate dimensions to fit through the cardiac catheter into the heart. The methods typically include gripping the edges of the two leaflets of the mitral valve, and securing them together using clasping, stitching, or suturing techniques. By connecting the leaves of the mitral valve together over a short length, the loss of tension in the leaves is reduced, and the remaining portions of the leaves have better coaptation and better perform the function of a one way valve by not permitting blood to flow in the wrong direction by regurgitation. The same approach as taken in repairing the mitral valve has been tried for repairing the tricuspid valve using clasps such as the clasp of the MitraClip®.
However, methods for repairing the mitral valve do not apply conveniently to a method for repairing the tricuspid valve. One major difference is that while the mitral valve has only two leaflets extending parallel with each other and which are relatively easy to grasp simultaneously, the tricuspid valve has three leaflets 52, 54, 56 that come to a common point of meeting, as seen in FIG. 2. The mechanical problems involved in grasping all three leaflets simultaneously at a single point are far more complex than with the mitral valve, because the operator is not presented with two elongated edges to grasp, but with three triangulated points that must be grasped simultaneously. By doing this, the tension in the leaflets is increased, and coaptation is improved.
Accordingly, there is a need in the art for a novel and advantageous method to grasp and connect the three leaves of the tricuspid valve at the common point of their meeting. The present invention addresses these, and other needs.